Growth to RTN

[Waters]

Your running carbon in a reactor yes?
Also gfo in a reactor?
And you've tried pulling the gfo entirely ?

You don't have outside air for the the skimmer? It's a scrubber. And no correlation on changing the media?

What other coral do you have? And have you been adding more during this time?

Yes, running both Carbon and GFO in separate reactors. I have not tried pulling GFO completely....maybe something that I will try if I cannot pinpoint the issues. No, no outside air for the skimmer....pulls air strictly from within a canister filled with Soda Ash. I was having my issues long before I started using that unfortunately. As for coral, I have a huge range lol. Everything from Montipora, Acros, Pocillopora, Millepora, Hammers, Elegance, Mushrooms, etc. I don't discriminate

 

[Hedgedrew66]

Yes, running both Carbon and GFO in separate reactors. I have not tried pulling GFO completely....maybe something that I will try if I cannot pinpoint the issues. No, no outside air for the skimmer....pulls air strictly from within a canister filled with Soda Ash. I was having my issues long before I started using that unfortunately. As for coral, I have a huge range lol. Everything from Montipora, Acros, Pocillopora, Millepora, Hammers, Elegance, Mushrooms, etc. I don't discriminate

Ya 15 percent per week with that salt and high intense light which you never described is exactly enough to fry acro.

 

[Hedgedrew66]

Do yourself a favor and switch to ESV or use instant ocean and dose it with little muriatic acid to lower alk and I think your problems go away.

 

[Hedgedrew66]

You also might want to try dosing some iron and iodine.

 

[saltyfilmfolks]

K. I was trying to rule it allopathy I think you may have running the carbon.

I suppose the nutints could be a thing. Personally I'm not a fan of propalctic gfo. But iv not head of this issue. I avoided it for a long time as when I did add small amounts my candy canes immediately became skeletons. And that was passive in a bag.

I think you'd see a pattern emerge there that conicides with feedings.

 

[Velcro]

Well, I am an idiot I have been using the Hanna checker, thinking I purchased the Low range...turns out it wasn't. I bought the low range meter and am getting a reading of 4, which would be .01464 after doing the math to convert it to phosphate. I assume that is OK or still too low?

Should be fine with that number

 

[TexasReefer82]

That Phosphate reading of 4ppb is quite low. Be aware that the accuracy on that Hanna Checker is +/- 5ppb. So, a reading of 4 could really be anywhere from 0-9ppb. You'd be better off to maintain a reading of around 16, that's 0.05 mg/L Phosphate. Additionally, a 16ppb reading on the Hanna checker is high enough above that gauge's limit of detection that it can't be confused with zero.

And I'll second a previous commenter by saying that very low/zero phosphate CAN indeed cause STN/RTN in acropora especially. I've been able to stop tissue necrosis in its tracks by dosing phosphate when it was zero. I dose both nitrate and phosphate to my 40g sps reef because if I don't the acropora will die.

My 2 cents: remove the GFO (and any other phosphate removers) completely and allow the phosphate to build up to a measurable level. My suspicion is that it won't - meaning that your corals are probably already using all the phosphate added to your tank, and the GFO itself probably isn't really absorbing anything. Corals consume more phosphate than many reefers realize.